Pseudo-phase equilibrium of light and heavy crude oils for enhanced oil recovery

Presented paper, herein, is on phase equilibrium of light and heavy crudes known to be closely related to enhanced oil recovery (EOR). In miscible gas injection, the advancing gas (or injecting fluid) develops with petroleum fluids a miscibility front in the reservoir fluids that further reduces the viscous forces holding crudes stranded. The present work presents a phase equilibrium scheme upon which heavy oil swelling and light crude vaporization were found when carbon dioxide (or methane) was used as advancing gas. Heavy crude swelling was observed to be not only dependent on gas solubility but also on the chemical composition of the crude oil. Although a small fraction of injecting gas was distributed in the reservoir water, the initial water–oil ratio was seen to alter the bubble-point pressure from 10 to 30 % depending of the injected gas. In order to mimic miscible-like behavior during gas injection, a dynamic description of methane and carbon dioxide was proposed. Alteration of PVT parameters below and beyond the bubble-point pressure was highlighted therefrom.